Evidence of Immunomodulatory Food-Protein Derived Peptides in Human Nutritional Interventions: Review on the Outcomes and Potential Limitations

Identification, characterization, and molecular docking of immunomodulatory peptides in Astragalus (Astragalus membranaceus (Fisch.)Bge) seed protein hydrolysates

Developing bioactive peptides from natural plant sources into functional foods and immunomodulators is becoming an attractive approach. In this study, the protein hydrolysates (APH) of Astragalus membranaceus (Fisch.)Bge seed was prepared by alkaline protease digestion method, and components with less than 3KDa were obtained by ultrafiltration (UAPH). The peptide sequence of UAPH was identified by UPLC-MS/MS. silico analysis screened 46 peptides with biological activity. Cell experiments and molecular docking results showed that UAPH can regulate the immune activity of RAW264.7 cells by enhancing cell phagocytic activity and ROS generation, upregulating the expression of TNF -α, IL-6, IL-1β, and TLR4. Peptides DWVSLPG, WVSLPGVP, and FTSIVGNVF are expected to contribute to the immune regulatory activity of UAPH. This study first discovered that the hydrolyzed protein of A. membranaceus seed is a source of immunomodulatory agents, revealing the potential of A. membranaceus seed peptides in developing novel and effective immunomodulatory functional foods.

Novel immunomodulatory peptides from hydrolysates of the Rana spinosa (Quasipaa spinosa) meat and their immunomodulatory activity mechanism

In this study, hydrolysates of Rana spinosa meat were purified and characterized, and combined with molecular docking to screen potential immunomodulatory peptides and explore their activities and mechanisms of action. The results showed that 582 peptides were identified from the hydrolysates, and three novel immunomodulatory peptides, GIHETTYNS (1020.4512 Da), IADRMQKE (989.4964 Da), and IVRDIKEK (999.6077 Da), were obtained by molecular docking. These peptides significantly increased the proliferative activity of RAW264.7 cells and accelerated its cell cycle proceeding, promoted the production of NO, IL-6, and TNF-α, and enhanced ROS levels. The molecular docking analysis revealed that immunomodulatory peptides bound to the key regions of TLR4/MD-2 by hydrogen bonds and hydrophobic interactions, and the common sites of action were LYS A:458, ARG A:434, and ARG D: 90. Furthermore, these immunomodulatory peptides had favorable safety and stability properties in silico analysis. These novel peptides are expected to be new natural materials for immunomodulators.

Immunonutrition: future perspective in neurodegenerative disorders

The relevance of lifestyle, including diet and exercise, has been associated with improved learning and memory capacity, delayed age-related cognitive decline, and a reduced risk of neurodegeneration. Most neurodegenerative diseases are defined as complex multifactorial disorders in which genetic and environmental factors greatly contribute to their onset. Although inflammatory cells produce reactive oxygen species (ROS), oxidative stress itself might exert pro-inflammatory effects and an uncontrolled response could lead to a state of chronic inflammation. Anti-inflammatory dietary approaches unify the disciplines of nutrition, immunity, and neurology. Personalized dietary interventions will be developed based on an individual's genetic makeup, metabolic profile, and gut microbiota composition, thanks to advances in genomics, metabolomics, and microbiome research. The relevance of dietary patterns in decreasing inflammation relies on the role of specific antioxidant nutrients, which might contribute to a decrease in the levels of ROS. This review aims to summarize recent advancements in neuroscience and immunology that have revealed the crucial role that diet and the immune system play in brain function and disease progression. Nutrition influences the immune system, and in turn, the immune system impacts neurological health. This bidirectional relationship suggests that targeted nutritional interventions could modulate immune responses to delay or mitigate the progression of neurodegenerative diseases potentially. This approach focuses on the use of specific nutrients and dietary components that influence the immune system and inflammatory pathway. Key elements of immunonutrition include omega-3 fatty acids, antioxidants, vitamins and various bioactive compounds found in foods.

The Role of Bioactive Compounds in Immunonutrition

The link between diet and immune function is a growing area of interest, recognized not only by the scientific community but also by global health organizations, such as the World Health Organization (WHO) [...].

Gastrointestinal digestion of food proteins: Anticancer, antihypertensive, anti-obesity, and immunomodulatory mechanisms of the derived peptides

Food proteins and their peptides play a significant role in the important biological processes and physiological functions of the body. The peptides show diverse biological benefits ranging from anticancer to antihypertensive, anti-obesity, and immunomodulatory, among others. In this review, an overview of food protein digestion in the gastrointestinal tract and the mechanisms involved was presented. As some proteins remain resistant and undigested, the multifarious factors (e.g. protein type and structure, microbial composition, pH levels and redox potential, host factors, etc.) affecting their colonic fermentation, the derived peptides, and amino acids that evade intestinal digestion are thus considered. The section that follows focuses on the mechanisms of the peptides with anticancer, antihypertensive, anti-obesity, and immunomodulatory effects. As further considerations were made, it is concluded that clinical studies targeting a clear understanding of the gastrointestinal stability, bioavailability, and safety of food-based peptides are still warranted.

Sacha Inchi (Plukenetia volubilis L.) Protein Hydrolysate as a New Ingredient of Functional Foods

Sacha inchi (Plukenetia volubilis L.) is an under-exploited crop with great potential due to its nutritional and medicinal characteristics. A Sacha inchi protein isolate (SII), obtained from defatted Sacha inchi flour (SIF), was hydrolyzed by Bioprotease LA 660 under specific conditions. The hydrolysates were characterized chemically, and their digestibility and antioxidant capacity were evaluated by in vitro cell-free experiments to select the hydrolysate with major antioxidant activity. Sacha inchi protein hydrolysate at 20 min (SIH20B) was selected, and the anti-inflammatory capacity was evaluated by RT-qPCR and ELISA techniques, using two different doses in monocytes THP-1 stimulated with lipopolysaccharide (LPS). The results obtained showed that the in vitro administration of SIH20B down-regulated the TNF-α gene and reduced the release of this cytokine, whereas the anti-inflammatory cytokines IL-10 and IL-4 were up-regulated in LPS-stimulated monocytes and co-administrated with SIH20B. The peptides contained in SIH20B were identified, and the 20 more relatively abundant peptides with a mass by 1 kDa were subjected to in silico analysis to hypothesize those that could be responsible for the bioactivity reported in the hydrolysate. From the identified peptides, the peptides AAGALKKFL and LGVKFKGGL, among others, are proposed as the most biologically actives. In conclusion, SIH20B is a novel, natural source of high-value-added biopeptides that could be used as an ingredient in formulations of food or nutraceutical compounds.

Egg Yolk Selenopeptides: Preparation, Characterization, and Immunomodulatory Activity

In this study, egg yolk selenium peptides (Se-EYP) were prepared using double-enzyme hydrolysis combined with a shearing pretreatment. The properties of the selenopeptides formed were then characterized, including their yield, composition, molecular weight distribution, antioxidant activity, in vitro digestion, and immunomodulatory activity. The peptide yield obtained after enzymatic hydrolysis using a combination of alkaline protease and neutral protease was 74.5%, of which 82.6% had a molecular weight <1000 Da. The selenium content of the lyophilized solid product was 4.01 μg/g. Chromatography-mass spectrometry analysis showed that 88.6% of selenium in Se-EYP was in the organic form, of which SeMet accounted for 60.3%, SeCys2 for 21.8%, and MeSeCys for 17.9%. After being exposed to in vitro simulated digestion, Se-EYP still had 65.1% of oligopeptides present, and the in vitro antioxidant activity was enhanced. Moreover, Se-EYP exhibited superior immune detection indices, including immune organ index, level of immune factors in the serum, histopathological changes in the spleen, and selenium content in the liver. Our results suggest that Se-EYP may be used as selenium-enriched ingredients in functional food products.

Protein-based nutritional strategies to manage the development of diabetes: evidence and challenges in human studies

Type 2 diabetes mellitus (T2DM) is one of the most prevalent diseases in modern society, governed by both genetic and environmental factors, such as nutritional habits. This metabolic disorder is characterized by insulin resistance, which is related to high blood glucose levels, implying negative health effects in humans, hindering the healthy ageing of people. The relationship between food and health is clear, and the ingestion of specific nutrients modulates some physiological processes, potentially implying biologically relevant changes, which can translate into a health benefit. This review aims to summarize human studies published in which the purpose was to investigate the effect of protein ingestion (in native state or as hydrolysates) on human metabolism. Overall, several studies showed how protein ingestion might induce a decrease of glucose concentration in the postprandial state (area under the curve), although it is highly dependent on the source and the dose. Other studies showed no biological effects upon protein consumption, mostly with fish-derived products. In addition, the major challenges and perspectives in this research field are highlighted, suggesting the future directions, towards which scientists should focus on. The dietary intake of proteins has been proven to likely exert a beneficial effect on diabetes-related parameters, which can have a biological relevance in the prevention and pre-treatment of diabetes. However, the number of well-designed human studies carried out to date to demonstrate the effects of specific proteins or protein hydrolysates in vivo is still scarce.